What are Humectants Doing to My Curls?

Humectants (Glycerin) and Curly Hair

Frizzy hair occurs when moisture passes through the cuticle layer of your hair from a hot-humid environment (subtropical climate or southeast side of all continents), allowing the hair strands to expand. In most cases, curly hair is more prone to frizz than straight hair because of having open cuticles at the ends leading to dehydration in strands.

Ingredients that tend to fight frizz are silicones, esters, and plant oils.

Siliconesbind to the hair, helping to smooth the cuticle and create a barrier that stops humidity from getting into the hair shaft. 

Hydrolyzed protein helping to smooth the cuticle and encouraging a fuller look while fighting frizz. Wheat, soy, and quinoa are a few examples. 

Esters aid in sealing and smoothing the hair cuticle to diminish the feel and appearance of frizz.

Plant oils are small enough to penetrate the hair cuticle to provide protection against frizzing caused by external factors like humidity. Cassava root, avocado, olive, coconut, and sunflower oil are examples.

Humectants are the main ingredients known to cause frizzing. The list of ingredients classified as humectants consist of but not limited to:

Allatonin
Aloe vera gel
Beeswax
Butylene glycol
Glycerin
Hydrolyzed silk protein
Panthenol
Propylene glycol
Sodium lactate 
Sodium PCA
Sorbitold

The most talked about humectant is Glycerin. But what in the world is it?

Glycerin is heavy in humectants, which are made to pull moisture into the hair and retain it. However, it also works the other way. Glycerin can work against you when the air is not humid enough by releasing moisture back into air.

Humectants are substances that draw out water, with dew points being the determining factor in figuring out when to use or avoid them.  Below list important dew points to note and their influence on frizzy hair: 

Dew Points Below 35 °F: humectants draw out the remaining moisture from your hair to the dry environment, leaving your hair dry and brittle. 

Between 30-45 and 60-70 °F: humectants draw water from the environment to your hair to make curls bouncy and tamed.  

Dew points above 60 °F: humectants draw more water to the hair which leads to frizzing.

In conclusion, it’s great to use glycerin based products in moderately moist air. Not too humid, not too dry. “Glycerin works best on natural hair when it is pulling moisture from the air to keep our tresses moisturized throughout the day,” says Erica Douglas, AKA cosmetic chemist Sister Scientist. “When used in the right climactic conditions, glycerin can really help to define your curl pattern! When used in the wrong conditions, it can lead to hair damage.” A leave-in spritz made with glycerin, water and essential oils can make curls and kinks very happy in the right climate. There’s a reason your grandma used rosewater and glycerin! It’s a great combo!

Here’s a full list of humectants you may find on the ingredient label.

1,2,6 hexanetriol
Butylene Glycol
Dipropylene glycol
Glycerin
Hexylene Glycol
Panthenol
Phytantriol — enhances moisture-retention, increases absorption of vitamins, panthenol, and amino acids into hair shaft, imparts gloss
Propylene glycol
Sodium PCA
Sorbitol
Triethylene glycol
Polyglyceryl sorbitol
Glucose
Fructose
Polydextrose
Potassium PCA
Urea
Hydrogenated Honey
Hyaluronic Acid
Inositol
Hexanediol beeswax
Hexanetriol Beeswax
Hydrolyzed Elastin
Hydrolyzed Collagen
Hydrolyzed Silk
Hydrolyzed Keratin
Erythritol
Capryl glycol
Isoceteth-(3-10, 20, 30)
Isolaureth-(3-10, 20, 30)
Laneth-(5-50)
Laureth-(1-30)
Steareth-(4-20)
Trideceth-(5-50)

https://www.essence.com/hair/natural/know-your-ingredients-truth-about-glycerin-natural-hair/